Journal articles on the topic 'Exclosure'
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Ibrahim, Temima, Fikrey Tesfay, and Bethel Geremew. "Diversity of Woody Species and Biomass Carbon Stock in Response to Exclosure Age in Central Dry Lowlands of Ethiopia." Open Environmental Research Journal 14, no. 1 (April 20, 2021): 1–12. http://dx.doi.org/10.2174/2590277602114010001.
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Objective: Empirical evidence on the potential of area exclosure in the restoration of severely degraded lands is crucially important. Thus, a study was conducted to examine the influence of exclosure age on vegetation structure, diversity, and biomass carbon stock in the central dry lowland of Ethiopia. Methods: Exclosures of 5, 15, >20 years old, and adjacent open grazing land were selected. Data on vegetation were collected using 20 × 20 m sampling quadrats which were laid along parallel transect lines. Results: The result showed that 17 woody species which represent 9 families were recorded at exclosures and open grazing lands. Shannon-Wiener (H') diversity index ranged from 0.74 (open grazing land) to 2.12 (middle age exclosure). Shannon evenness (E) index was higher in the middle age exclosure (0.80). Woody species basal area and tree density significantly (p < 0.05) increased with increasing exclosure age. The Aboveground woody biomass significantly (p < 0.05) varied from 12.60 (open grazing land) to 68.61 Mg ha-1 (middle age exclosure). Similarly, the aboveground biomass (AGB) carbon stocked was significantly (p < 0.05) higher in the middle (32 Mg ha-1) and old age exclosures (31 Mg ha-1). Conclusion: This study indicated that exclusion can restore the degraded vegetation and sequester and stock more atmospheric carbon dioxide in the aboveground biomass. Therefore, open degraded grazing land of the lowland areas can be restored into a promising stage through area exclosure land use management.
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Bastin, Gary, John Ludwig, Robert Eager, Adam Liedloff, Reginald Andison, and Michael Cobiac. "Vegetation changes in a semiarid tropical savanna, northern Australia: 1973 - 2002." Rangeland Journal 25, no. 1 (2003): 3. http://dx.doi.org/10.1071/rj03001.
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We measured vegetation changes inside and outside two exclosures built in 1973 on red calcareous loam soils located in Conkerberry Paddock on Victoria River Research Station in northern Australia. These two exclosures were unburnt since their establishment in 1973 until exclosure 1 was unintentionally burnt late in the dry season (October) of 2001. Data from permanent transects and examples from photopoints illustrate that from mostly bare soils in 1973, total pasture biomass recovered relatively rapidly both inside and outside exclosures (in about five years). This initial recovery was primarily due to the establishment of annual grasses and forbs. After this five year period, there was a consistent increase in the biomass of perennial grasses, such as Heteropogon contortus and Dichanthium spp. Also in the first five years after exclosure, the exotic shrub, Calotropis procera,invaded the study area, but then largely disappeared in a period of lower wet-season rainfall in the late 1980s. The density of native tree species, particularly Hakea arborescens, Eucalyptus pruinosa and Lysiphyllum cunninghamii increased in general, but more so inside one or other of the exclosures. Although the late dry-season fire of 2001 reduced the density of larger H. arborescens and L. cunninghamii inside the exclosure at Site 1, this effect was not apparent for smaller trees and for trees outside this exclosure. Our findings show that savanna vegetation can change massively in the medium term (29 years) and that exclosure from cattle grazing can contribute to our understanding of the role of livestock in such change. However, exclosures by themselves do not provide adequate information about the processes leading to vegetation change replicated experimental studies are needed. That substantial increase in the biomass and proportion of perennial grasses occurred with light to moderate cattle grazing implies that these rangelands can be managed for production, although control of woody vegetation is an issue.
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Mekuria, Wolde. "Changes in Regulating Ecosystem Services following Establishing Exclosures on Communal Grazing Lands in Ethiopia: A Synthesis." Journal of Ecosystems 2013 (June 26, 2013): 1–12. http://dx.doi.org/10.1155/2013/860736.
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In four separate studies undertaken in the northern highlands of Ethiopia, changes in regulating ecosystem services, economic viability, and the perception of local communities following establishing exclosures on communal grazing lands were investigated. Replicated 5-, 10-, 15-, and 20-year-old exclosures were selected and paired each exclosure with an adjacent grazing land. All exclosures displayed higher ecosystem services than communal grazing lands. Differences between exclosures and grazing lands varied between 29 (±4.9) and 61 (±6.7) Mg C ha−1 for ecosystem carbon stock (ECS), 2.4 (±0.6) and 6.9 (±1.8) Mg ha−1 for total soil N stock, and 17 (±3) to 39 (±7) Kg ha−1 for the available P stock, and all differences increased with exclosure duration. Differences in plant species richness and biomass between an exclosure age and communal grazing land were higher in oldest than in youngest exclosures. Over a period of 30 years, sequestered carbon dioxide was 246 Mg ha−1, total soil nitrogen increased by 7.9 Mg ha−1, and additional available phosphorous stocks amounted to 40 kg ha−1. The Net Present Value of exclosures ecosystem services under consideration was about 28% (837 US$) higher than alternative wheat production indicating that exclosures are competitive to alternative land uses. There are substantial opportunities to mobilize the local communities in efforts to establish exclosures, given that more than 75% had a positive view on exclosures effectiveness to restore degraded ecosystems. Establishing exclosures on communal grazing lands can be effective for restoring degraded ecosystems and the services that they provide.
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Kirkpatrick, J. B., and K. L. Bridle. "Comparative Effects of Stock and Wild Vertebrate Herbivore Grazing on Treeless Subalpine Vegetation, Eastern Central Plateau, Tasmania." Australian Journal of Botany 47, no. 6 (1999): 817. http://dx.doi.org/10.1071/bt98029.
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The existence of two 25-year-old grazing exclosures on Liawenee Moor, Eastern Central Plateau, Tasmania, created an opportunity to investigate the impacts of vertebrate herbivores on treeless subalpine vegetation. There were three treatments: sheep-, native herbivore- and rabbit-grazed; native herbivore- and rabbit-grazed; no grazing. The amount of bare ground was highest in the sheep-grazed plots, while vegetation cover was greatest in the ungrazed exclosure. The cover of all lifeform groups, except small herbs, was greater in the exclosures than in the sheep-grazed plots. The percentage frequency of tall herbs was significantly less in the sheep-grazed plots than either of the grazing exclosures. Tall herbs were more likely to be found under the canopy of other vegetation in the sheep-grazed plots while the same species were found to be growing in locations with no other vegetation cover in the ungrazed exclosure. Revegetation of bare ground averaged 1% per year over a 20-year period in the ungrazed exclosure. While percentage bare ground has also decreased in the native- and rabbit-grazed exclosure, it has increased in the sheep-grazed plots. Domestic stock grazing appears to have a much greater impact on vegetation cover, species composition and community structure than grazing by native herbivores and rabbits. No grazing allows for the fastest rehabilitation of the area. Our results are consistent with those from alpine and treeless subalpine areas of the Australian mainland.
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Bode, Michael, Karl E. C. Brennan, Keith Morris, Neil Burrows, and Neville Hague. "Choosing cost-effective locations for conservation fences in the local landscape." Wildlife Research 39, no. 3 (2012): 192. http://dx.doi.org/10.1071/wr11106.
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Context Exclosure fences are widely used to reintroduce locally extinct animals. These fences function either as permanent landscape-scale areas free from most predators, or as small-scale temporary acclimatisation areas for newly translocated individuals to be ‘soft released’ into the wider landscape. Existing research can help managers identify the best design for their exclosure fence, but there are currently no methods available to help identify the optimal location for these exclosures in the local landscape (e.g. within a property). Aims We outline a flexible decision-support tool that can help managers choose the best location for a proposed exclosure fence. We applied this method to choose the site of a predator-exclusion fence within the proposed Lorna Glen (Matuwa) Conservation Park in the rangelands of central Western Australia. Methods The decision was subject to a set of economic, ecological and political constraints that were applied sequentially. The final exclosure fence location, chosen from among those sites that satisfied the constraints, optimised conservation outcomes by maximising the area enclosed. Key results From a prohibitively large set of potential exclosure locations, the series of constraints reduced the number of candidates down to 32. When ranked by the total area enclosed, one exclosure location was clearly superior. Conclusions By describing the decision-making process explicitly and quantitatively, and systematically considering each of the candidate solutions, our approach identifies an efficient exclosure fence location via a repeatable and transparent process. Implications The construction of an exclusion fence is an expensive management option, and therefore needs to convincingly demonstrate a high expected return-on-investment. A systematic approach for choosing the location of an exclosure fence provides managers with a decision that can be justified to funding sources and stakeholders.
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Otsu, Chiaki, Hayato Iijima, and Takuo Nagaike. "Plant community recovery from intense deer grazing depends on reduction of graminoids and the time after exclosure installation in a semi-natural grassland." PeerJ 7 (October 1, 2019): e7833. http://dx.doi.org/10.7717/peerj.7833.
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Exclosures that exclude large herbivores are effective tools for the protection and restoration of grazed plant communities. However, previous studies have shown that the installation of an exclosure does not ensure plant community recovery. Our study aimed to determine the effects of the domination of unpalatable plants and the timing of exclosure installation on the plant community recovery process in montane grassland overgrazed by sika deer (Cervus nippon) in Japan. In this study we compared plant species composition and their cover with inside and outside exclosures installed at different times. Furthermore, we also compared them with those in 1981, when density of sika deer was very low. We used quadrats inside and outside fenced areas established in 2010 and 2011 to record both the cover and the height of species in each quadrat between 2011 and 2015. Plant cover, with the exception of graminoid species, increased in later years in all treatments. Non-metric multidimensional scaling (NMDS) plots showed significantly differentiated treatment trends. The species composition within the 2010 fenced area gradually shifted to greater similarity with the species composition reported in 1981. The plant community in the 2011 fenced area was slower to recover. Compositions of plant communities outside the fenced areas hardly changed from 2011 to 2015. Chao’s dissimilarity index decreased over time between the plant community surveyed between 2011 and 2015 and the past plant community in 1981 within the exclosures, and was higher in the 2011 fenced area than in the 2010 fenced area. In conclusion, we show that the reduction of graminoids and the time after exclosure installation were important for plant community recovery from deer grazing damage. A delay in exclosure installation of one year could result in a delay in plant community recovery of more than one year.
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Gerke, Madlen, Daniel Cob Chaves, Marc Richter, Daniela Mewes, Jörg Schneider, Dirk Hübner, and Carola Winkelmann. "Benthic grazing in a eutrophic river: cascading effects of zoobenthivorous fish mask direct effects of herbivorous fish." PeerJ 6 (February 14, 2018): e4381. http://dx.doi.org/10.7717/peerj.4381.
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Benthic grazing strongly controls periphyton biomass. The question therefore arises whether benthic grazing could be used as a tool to reduce excessive growth of periphyton in nutrient-enriched rivers. Although benthic invertebrate grazers reduce the growth of periphyton, this is highly context dependent. Here we assessed whether the only obligate herbivorous fish in European rivers, the common nase (Chondrostoma nasus L.), is able to reduce periphyton biomass in a eutrophic river. We conducted three consecutive in situ experiments at low, intermediate and high densities of nase in the river using standard tiles on the river bottom naturally covered with periphyton that were accessible to fish and tiles that excluded fish foraging with electric exclosures. The biomass of benthic invertebrate grazers was very low relative to nase. We hypothesised that nase would reduce periphyton biomass on accessible tiles and therefore expected higher periphyton biomass on the exclosure tiles, at least at intermediate and high densities of nase in the river. Contrary to our expectation, the impact of fish grazing was low even at high fish density, as judged by the significantly lower chlorophyll a concentration on exclosure tiles even though the ash-free dry mass on accessible and exclosure tiles did not differ. The lower chlorophyll a concentrations on exclosure tiles might be explained by a higher biomass of invertebrate grazers on the exclosure tiles, which would indicate that the effect of invertebrate grazers was stronger than that of herbivorous fish grazers. The high biomass of invertebrate grazers on exclosure tiles likely arose from the exclusion of zoobenthivorous fish, which occur in the river at high densities. The results of our small-scale experiments suggested that cascading top-down effects of zoobenthivorous fish have a higher impact on periphyton biomass than direct effects of herbivorous nase.
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Abendroth, Emily. "Exclosure ]12[." WSQ: Women's Studies Quarterly 41, no. 3-4 (2013): 151–53. http://dx.doi.org/10.1353/wsq.2013.0096.
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Christianini, AV, and M. Galetti. "Toward reliable estimates of seed removal by small mammals and birds in the Neotropics." Brazilian Journal of Biology 67, no. 2 (May 2007): 203–8. http://dx.doi.org/10.1590/s1519-69842007000200004.
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Birds are often considered seed predators of less importance when compared to rodents or granivorous ants in studies of seed predation using selective exclosures. However, it is possible that the role of granivorous birds interacting with seeds on the floor of Neotropical forests is being underestimated, if the selective exclosures designed to allow exclusive access to small rodents do not work properly in the Neotropics. We used an experimental approach to evaluate whether birds could remove seeds from selective exclosures designed to allow exclusive access to rodents. We compared seed removal from two paired treatments in the field: an open treatment (control) allowing the access to all vertebrates, and a selective exclosure treatment, where seeds were placed under a cage staked to the ground and covered on top and on the laterals by wire mesh of varying sizes. Treatments were placed in the center of a sand quadrat in order to record the visit of vertebrates from their footprints. Although the selective exclosures are used to tell apart the small mammal seed removal from that of other animals, birds could persistently remove seeds from selective exclosures. Thus, the role of birds interacting with seeds on the floor of tropical forests may be underestimated for some plant species, due to an artifact of the exclosure method employed. Exclosures of 40 x 40 x 40 cm should be efficient to deter the removal of seeds by birds, allowing the consumption of the seeds by small mammals at the same time.
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Courchesne, Milène, Stéphanie Pellerin, Marianne Bachand, Steeve D. Côté, and Monique Poulin. "Chronic deer browsing leads to biotic homogenization of minerotrophic peatlands." Botany 96, no. 8 (August 2018): 499–509. http://dx.doi.org/10.1139/cjb-2017-0145.
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Peatlands could become important foraging habitats, and their plant communities threatened, in areas with an overabundance of large herbivores. Peatland response to herbivore exclusion may vary widely according to abiotic conditions and associated species because of a strong minerotrophic gradient. We assessed the impact of white-tailed deer (Odocoileus virginianus Zimm.) on peatland vegetation using an exclosure experiment. A total of 53 pairs of exclosures and unprotected plots were set up in bogs (13 pairs), sedge fens (20), shrub fens (7), and laggs (13), and surveyed prior to exclosure construction as well as three, five, and eight years after. Vascular plant composition of exclosures diverged from that of unprotected plots through time only in shrub fens and laggs. Bryophytes remained constant in all habitats. On average, shrub cover was 30% higher in exclosures in all habitats after five years, whereas herb cover increased only in laggs, by 43%, after eight years. Reclassification of sites by pH showed deer exclusion promoted alpha diversity in low- and high-moderate rich fens (pH 5.3–6.8) and beta diversity in the latter as well as in rich fens (pH 6.3–7.5). Overall, our results suggest that conservation efforts in areas with overabundant large herbivores should target richer peatland habitats since they showed a higher resilience and fostered alpha and beta diversity.
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Liu, Jian, Weijun Xu, Qiuyu Wang, and Kuijun Zhao. "Insect predators in northeast China and their impacts on Aphis glycines." Canadian Entomologist 144, no. 6 (November 19, 2012): 745–55. http://dx.doi.org/10.4039/tce.2012.70.
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AbstractPredators of Aphis glycines Matsumura (Hemiptera: Aphididae) were surveyed and their ability to suppress A. glycines population growth was determined in Harbin, northeast China (45.4°N, 126.4°E). Field surveys were conducted on 21 fixed sampling sites in 2004 and 17 in 2005. Impacts of natural enemies of A. glycines were studied using exclosure experiments. Thirteen natural enemies were found, the most abundant of which was Propylaea japonica (Thunberg), Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae), Chrysopa sinica Tjeder, Chrysopa phyllochroma Wesmael, Chrysopa formosa Brauer (Neuroptera: Chrysopidae), Hemerobius humuli Linnaeus (Neuroptera: Hemerobiidae), Orius Wolff sp. (Heteroptera: Anthocoridae), Nabis stenoferus Hsiao (Heteroptera: Reduviidae), Deraeocoris punctulatus (Fallén) (Heteroptera: Miridae), and Episyrphus balteata (De Geer) (Diptera: Syrphidae). Three exclosure treatment types were established, large-mesh cages, small-mesh cages, and no cages. In exclosures, A. glycines density in small-mesh cages peaked at numbers 3.75-fold higher than in large-mesh cages and 17.44-fold higher than on plants with no cages in 2004. In 2005, these numbers were 4.59-fold and 60.98-fold. Temperature was not a factor in exclosures, but relative humidity had significant effects. These results indicated that existing predator communities could partially suppress soybean aphid population density in soybean fields in northeast China.
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Zou, J., L. Zhao, S. Xu, X. Xu, D. Chen, Q. Li, N. Zhao, C. Luo, and X. Zhao. "Field <sup>13</sup>CO<sub>2</sub> pulse labeling reveals differential partitioning patterns of photoassimilated carbon in response to livestock exclosure in a <i>Kobresia</i> meadow." Biogeosciences 11, no. 16 (August 20, 2014): 4381–91. http://dx.doi.org/10.5194/bg-11-4381-2014.
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Abstract. Livestock exclosure has been widely used as an approach for grassland restoration. However, the effects of exclosures on grasslands are controversial and can depend on many factors, such as the grassland ecosystem types, evolutionary history and so on. In this study, we conduct field experiments to investigate the variations of the ecosystem function in response to livestock exclosure in a Kobresia humilis meadow with 6 years of grazing exclosure on the Qinghai–Tibetan Plateau. We focused on two ecosystem functions: plant community structure and ecosystem carbon cycling. The plant aboveground productivity, plant diversity and the composition of plant functional groups of the meadow were addressed as the indicators of the plant community structure. The 13C isotope pulse labeling technique was applied to evaluate the alterations of ecosystem carbon cycling during a short term. The results showed that the plant community structure was changed after being fenced in for 6 years, with significantly decreased aboveground productivity, species loss and varied composition of the four plant functional groups (grasses, sedges, legumes and forbs). Using the pulse labeling technique, we found a lower cycling rate of 13C in the plant–soil system of the fenced plots compared with the grazed sites during the first 24 h after labeling. A higher proportion of recovered 13C in the plant–soil system migrated into the soil as root exudates immediately after labeling at both fenced and control grazed sites, with a significantly lower proportion in the fenced site, coinciding with the lower proportion of 13C lost from soil respiration. Thirty-two days after labeling, 37% of the recovered 13C remained in the soil of the fenced plots, with significant differences compared to in the grazed plots (47%). In addition, less 13C (5 vs. 7%) was lost by soil respiration in the fenced plots during the chase period of 32 days. Overall, our study suggests that livestock exclosures have negative effects on the plant community structure and partitioning patterns of the photoassimilated carbon in the Kobresia meadow, and the effects on photoassimilated carbon cycling are likely to result from the variations of community structures in the ecosystem.
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PUGLIESE, A., and R. ROSÀ. "Effect of host populations on the intensity of ticks and the prevalence of tick-borne pathogens: how to interpret the results of deer exclosure experiments." Parasitology 135, no. 13 (April 28, 2008): 1531–44. http://dx.doi.org/10.1017/s003118200800036x.
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SUMMARYDeer are important blood hosts for feeding Ixodes ricinus ticks but they do not support transmission of many tick-borne pathogens, so acting as dead-end transmission hosts. Mathematical models show their role as tick amplifiers, but also suggest that they dilute pathogen transmission, thus reducing infection prevalence. Empirical evidence for this is conflicting: experimental plots with deer removal (i.e. deer exclosures) show that the effect depends on the size of the exclosure. Here we present simulations of dynamic models that take into account different tick stages, and several host species (e.g. rodents) that may move to and from deer exclosures; models were calibrated with respect to Ixodes ricinus ticks and tick-borne encephalitis (TBE) in Trentino (northern Italy). Results show that in small exclosures, the density of rodent-feeding ticks may be higher inside than outside, whereas in large exclosures, a reduction of such tick density may be reached. Similarly, TBE prevalence in rodents decreases in large exclosures and may be slightly higher in small exclosures than outside them. The density of infected questing nymphs inside small exclosures can be much higher, in our numerical example almost twice as large as that outside, leading to potential TBE infection risk hotspots.
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Li, Yu, Shikui Dong, Qingzhu Gao, Yong Zhang, Shiliang Liu, David Swift, Jinbo Zhao, et al. "Grazing promotes plant functional diversity in alpine meadows on the Qinghai-Tibetan Plateau." Rangeland Journal 41, no. 1 (2019): 73. http://dx.doi.org/10.1071/rj18091.
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Grazing exclosures and rotational grazing have been extensively applied to prevent grassland degradation and to restore grassland ecosystem function and services. The mechanisms associated with changes in alpine plant traits, and functional diversity under different grazing regimes have not been deeply explored. We examined the variations of plant leaf traits and functional diversity of an alpine meadow under different grazing regimes in a 3-year experiment. The results showed, after 3 years of yak grazing, that the coverage of Stipa capillata increased, whereas that of Kobresia pygmaea decreased under grazing exclosure. Stipa capillata had a lower ratio of leaf nitrogen content to phosphorus content (N:P) under grazing exclosure than under rotational grazing and continuous grazing, whereas Kobresia pygmaea showed no significant differences among grazing treatments. Among grazing regimes, the specific leaf area (SLA) of Stipa capillata was similar, whereas that of Kobresia pygmaea was higher under grazing exclosure. At the interspecific level, leaf area and weight were negatively correlated with SLA, whereas leaf carbon (C) content, leaf N content, leaf C:P and leaf N:P were negatively related to leaf P content and leaf C:N. These findings indicated that growth-defence trade-off strategies might lead to variations in plant traits and coverage. Large-leaved species, due to high maintenance costs, were less commonly distributed in the community, and they were better defended and unpalatable to yaks due to lower SLA, this formed the species coverage distribution pattern of the community. Various N and P utilisation efficiency of different species indicated diverse economic resources utilisation strategies might be due to niche differentiation in the community. Plots that had been excluded from grazing had the lowest functional richness, evenness, and divergence. Rotational and continuous grazing were equivalent in promoting alpine plant functional diversity.
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Moore, J. E., and R. K. Swihart. "Factors affecting the relationship between seed removal and seed mortality." Canadian Journal of Zoology 86, no. 5 (May 2008): 378–85. http://dx.doi.org/10.1139/z08-011.
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S.B. Vander Wall et al. (Ecology, 86: 801–806 (2005)) criticized seed dispersal studies that use seed removal as a proxy for seed predation, because secondary dispersal processes following removal are important to seed fates for many plants. We compared seed removal rates with direct estimates of seed mortality and another mortality index, based on a 3-year experiment that included five temperate deciduous tree species and four exclosure treatments designed to identify effects of different seed consumer groups. Patterns of seed removal rates generally did not match patterns of mortality. Removal and mortality rates were both highest in seed-poor years, indicative of response to food limitation, but annual food abundance interacted with seed type differently for removal rates than for mortality rates. The effect of exclosure type (access by different consumers) on removal rates was opposite its effect on mortality rates; seeds were removed fastest from exclosures that allowed access to tree squirrels (genus Sciurus L., 1758), but these seeds had the lowest mortality because Sciurus is an important seed disperser. We discuss types of studies in which seed removal may be a reasonable index of seed mortality, and we stress the importance of justifying assumptions concerning links between removal and predation.
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Misebo, Amisalu Milkias, Samuel Feyissa Ayano, and Marcin Pietrzykowski. "Effects of Natural Rehabilitation of Degraded Land by Exclosure on Selected Soil Physicochemical Properties in Eastern Ethiopia." Agronomy 11, no. 8 (August 16, 2021): 1628. http://dx.doi.org/10.3390/agronomy11081628.
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The use of exclosure for ecological restoration has become an increasingly vital approach to reversing degraded lands. Its effectiveness in restoring degraded lands could be varied with differences in climate, vegetation type and soil properties. Thus, the objective of this study was to determine the effect of exclosure on the selected physical and chemical properties of the soil. A six-year-old exclosure and adjacent open land with the same history of land-use types were selected. Soil samples were randomly collected from 0–20 and 20–40 cm depths of each land-use type and measured for texture, soil moisture content (SMC), bulk density (BD), soil organic carbon (SOC), available phosphorus (Av.P), cation exchange capacity (CEC), electrical conductivity (EC) and pH contents. The highest SMC, SOC and Av.P and the lowest BD values were measured from the exclosure. SMC, SOC and Av.P increased by 73, 51 and 55%, respectively, while BD decreased by 31% as compared to the open land. CEC, EC and pH were also influenced positively compared with the adjacent open land. The funding indicates exclosure had a positive effect on the restoration of soil nutrients, which are essential to promote vegetation growth and thereby minimize soil erosion.
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Foster, C. N., and B. C. Scheele. "Feral-horse impacts on corroboree frog habitat in the Australian Alps." Wildlife Research 46, no. 2 (2019): 184. http://dx.doi.org/10.1071/wr18093.
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Context Introduced herbivores can have a substantial impact on native plants and animals, particularly in ecosystems that do not share a recent evolutionary history with similar herbivore species. The feral horse, Equus caballus, has a widespread but patchy distribution in Australia, with large populations present in national parks in the Australian Alps. There are few peer-reviewed studies of the impacts of feral horses on ecosystems in this region. However, impacts could be substantial, particularly in wetland and riparian environments that are focal points for horse activity and sensitive to trampling and physical disturbance. Aims In the present study, we used replicated horse exclosures to investigate the effects of feral horses on breeding habitat of the critically endangered northern corroboree frog, Pseudophryne pengilleyi, in the Australian Alps. Methods Pseudophryne pengilleyi constructs nests and lays eggs in dense litter surrounding small, seasonally flooded wetland pools. In 2010, we sampled the litter depth adjacent to pools at eight long-term P. pengilleyi monitoring sites. In 2011, horse exclosures were established at each of the eight sites, such that less than half of the wetland area was inside the exclosure. In 2015, we measured litter depth surrounding pools inside and outside the exclosures, as well as at three additional sites where feral horses were absent. Key results We found that the pool-edge litter was 1.9 times deeper in areas without horses (inside horse-exclosure plots and horse-free sites) than in areas accessible to horses (unfenced areas in horse-occupied sites). Conclusions Our study has presented experimental evidence that horse grazing and trampling reduce breeding-habitat quality for P. pengilleyi, which could result in reduced reproduction success. Implications Ensuring the persistence of high-quality habitat is crucial for the conservation of P. pengilleyi, particularly given the severity of the decline of this species associated with chytrid fungus. Our results have provided direct evidence of a negative feral-horse impact on the habitat of a threatened animal species in the Australian Alps.
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Austrheim, Gunnar, and Ove Eriksson. "Recruitment and life-history traits of sparse plant species in subalpine grasslands." Canadian Journal of Botany 81, no. 2 (February 1, 2003): 171–82. http://dx.doi.org/10.1139/b03-010.
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Recruitment is critical for the maintenance of plant populations and community diversity, but sexual regeneration is considered to be infrequent in climatically harsh habitats such as subalpine grasslands. This study examines the importance of regeneration through seed for 16 sparse herb species, and we asked whether their populations are limited by safe sites or the availability of seeds. Seedling recruitment and winter survival were recorded after sowing in an experimental split-plot design in (i) pasture grazed by livestock, and (ii) exclosed grassland cultivated for annual mowing. In addition we examined the effect of disturbance and local seedbank recruitment. All species were able to recruit and survive the first winter in at least some of the experimental plots, although none were initially present. Recruitment mainly occurred in disturbed plots, and disturbed pasture plots had a significantly higher recruitment than disturbed exclosures for all species except Silene dioica. We further examined whether specific plant traits were related to variation in recruitment. Lower recruitment in the disturbed exclosure was associated with higher specific leaf area, leaf dry weight, and seed number. In contrast, seeds sown in disturbed pasture recruited more independently of species traits. The exception was a negative correlation between recruitment and leaf dry weight, and an unexpected negative correlation with seed weight. We suggest that recruitment differences among habitats mainly reflect lower humidity in the exclosure. Consequently, small stature plants with small specific leaf area should have the highest recruiting probability when exposed to drought. The almost exclusive recruitment on disturbed plots indicates a strong competitive effect on the target species in vegetated plots, and suggests that safe sites for regeneration through seed are rare in subalpine grasslands.Key words: colonization, herbs, plant abundance and distribution, disturbance, pastures, cultivated exclosures, sowing experiment.
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Beschta, Robert L., Luke E. Painter, Taal Levi, and William J. Ripple. "Long-term aspen dynamics, trophic cascades, and climate in northern Yellowstone National Park." Canadian Journal of Forest Research 46, no. 4 (April 2016): 548–56. http://dx.doi.org/10.1139/cjfr-2015-0301.
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We report long-term patterns of quaking aspen (Populus tremuloides Michx.) recruitment for five ungulate exclosures in the northern ungulate winter range of Yellowstone National Park. Aspen recruitment was low (<3 aspen·ha−1·year−1) in the mid-1900s prior to exclosure construction due to herbivory by Rocky Mountain elk (Cervus elaphus Linnaeus, 1758) but increased more than 60-fold within 25 years after exclosure construction despite a drying climatic trend since 1940. Results support the hypothesis that long-term aspen decline in Yellowstone’s northern range during the latter half of the 20th century was caused by high levels of ungulate herbivory and not a drying climate. Gray wolves (Canis lupus Linnaeus, 1758) were reintroduced during 1995–1996. For the period 1995–2012, we summarized annual predator–prey ratios, ungulate biomass, and drought severity. The average density of young aspen increased from 4350 aspen·ha−1 in 1997–1998 to 8960 aspen·ha−1 in 2012; during the same time period, those >1 m in height increased over 30-fold (from 105 to 3194 aspen·ha−1). Increased heights of young aspen occurred primarily from 2007 to 2012, a period with relatively high predator–prey ratios, declining elk numbers, and decreasing browsing rates. Consistent with a re-established trophic cascade, aspen stands in Yellowstone’s northern range have increasingly begun to recover.
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Hanley, Thomas A. "Physical and chemical response of understory vegetation to deer use in southeastern Alaska." Canadian Journal of Forest Research 17, no. 3 (March 1, 1987): 195–99. http://dx.doi.org/10.1139/x87-034.
Full textAbstract:
Biomass of understory vegetation was sampled inside and outside four 19- to 21-year-old deer enclosures in the Alexander Archipelago of southeastern Alaska. Three sites were old-growth forests of western hemlock (Tsugaheterophylla (Raf.) Sarg.) –Sitka spruce (Piceasitchensis (Bong.) Carr.) and one site was an even-aged spruce–hemlock stand. In vitro dry-matter digestibility, fiber, nitrogen, and phosphorus concentrations of western hemlock seedlings and Alaska blueberry (Vacciniumalaskensis How.) inside and outside each exclosure also were compared. Analysis of variance indicated that Alaska blueberry and trailing bramble (Rubuspedatus Sm.) had greater biomass inside than outside the exclosures. No differences in chemical composition or digestibility of blueberry or hemlock inside and outside the exclosures occurred across sites. Results indicated that although deer may exert moderate to strong influence on the species composition and biomass of forest understories, their effect on dry-matter digestibility, fiber, nitrogen, and phosphorus concentrations of individual species may be negligible.
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ICKES, KALAN, SAARA J. DEWALT, and S. APPANAH. "Effects of native pigs (Sus scrofa) on woody understorey vegetation in a Malaysian lowland rain forest." Journal of Tropical Ecology 17, no. 2 (March 2001): 191–206. http://dx.doi.org/10.1017/s0266467401001134.
Full textAbstract:
Large mammals often play important roles in determining the structure and composition of plant communities. This study focused on the extent to which wild pigs (Sus scrofa) influence the dynamics of tree seedlings and saplings in a lowland rain forest at Pasoh Forest Reserve in West Malaysia. Native wild pigs are common in the study area and may significantly influence growth and survivorship of woody plants in the understorey through several activities namely, nest building, soil rooting and seed predation. To test experimentally the impact of pigs on the plant community, eight 49-m2 exclosures were constructed. After 2 y, the number of recruits inside exclosures was three times greater than in unfenced control plots. Stem density was highly correlated with species richness, which also increased significantly inside exclosures. Height growth of plants was greater in the exclosures by 52.5% for trees between 1 and 7 m tall. Trees less than 1 m tall, however, exhibited no differences in growth. Mortality of plants also did not differ between treatments. The observed differences between exclosure and control plots can be attributed to soil-rooting and seed predation, suggesting that these two behaviours of wild pigs are important to plant dynamics in the understorey.
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Bucher, Roman, Jonas Rochlitz, Nathalie Wegner, Anna Heiß, Alexander Grebe, Dana G. Schabo, and Nina Farwig. "Deer Exclusion Changes Vegetation Structure and Hunting Guilds of Spiders, but Not Multitrophic Understory Biodiversity." Diversity 13, no. 1 (January 12, 2021): 25. http://dx.doi.org/10.3390/d13010025.
Full textAbstract:
Ungulate herbivores modify plant community compositions, which can modulate biodiversity at higher trophic levels. However, these cascading effects on herbivorous and predatory arthropods in forest ecosystems remain poorly understood. We compared plant and arthropod communities between fenced exclosures and unfenced control plots in a permanent forest in Germany. After five years of deer exclusion, we quantified plant diversity and vegetation structure as well as the diversity of insects and spiders in 32 pair-wise plots. In addition, we compared spider communities with respect to different hunting guilds because they are expected to have different requirements for vegetation structure. Although we did not find differences in plant communities, vegetation height and heterogeneity were higher in exclosures compared to control plots. The diversity of insects and spiders was not affected by deer presence. However, the abundance of sheet-web weavers and ambush hunters was lower in exclosures whereas ground hunters were more common in exclosure plots. Structural changes in the vegetation changed predator hunting guilds even though mere abundance and biodiversity indices were not affected. We therefore suggest that monitoring of vegetation structure and associated functional groups seems more sensitive to assess the impact of ungulate herbivores compared to taxonomic metrics.
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Reddy, E., D. H. Van Vuren, P. G. Scowcroft, J. B. Kauffman, and L. Perry. "Long-term response of the mamane forest to feral herbivore management on Mauna Kea, Hawaii." Pacific Conservation Biology 18, no. 2 (2012): 123. http://dx.doi.org/10.1071/pc120123.
Full textAbstract:
Seven exclosure sites located on Mauna Kea, Hawaii and established in the 1960s and 70s were sampled to characterize long-term response of the mamane (Sophora chrysophylla) forest to protection from feral sheep grazing, and to assess impacts of non-native plant species and recurrent sheep presence on forest recovery. The forest provides essential habitat for an endangered bird, the palila (Loxoides bailleui). Vegetation was sampled inside exclosures during 1972–1976, 1998, and 2009, and also outside exclosures during 2009. Patterns of response varied among exclosures, but overall, mamane trees and native shrubs showed increasing cover between the 1970s and 1998, then a slowed rate of increase in cover or a decline between 1998 and 2009. Cover of native herbaceous vegetation showed variable trends between the 1970s and 1998, and then appeared to decline between 1998 and 2009. Mamane height class distributions inside exclosures indicated that recruitment was initially high but then declined as heights shifted toward larger size classes, and presumably an older age distribution. We found limited evidence of a negative effect of non-native species on forest regrowth, but the effect was not consistent over time or among sites. Recurrent sheep presence outside exclosures negatively affected mamane canopy density and perhaps tree density at all sites, and mamane condition at some sites. Our results indicate that the mamane forest has shown substantial regrowth inside exclosures at some sites, especially those protected the longest. However, these exclosures represent a small portion of the mamane forest. Sheep presence continues to impact mamane recovery outside exclosures, and thus habitat quality for the palila.
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Stuart-Smith, A. Kari, and Stan Boutin. "Prédation on red squirrels during a snowshoe hare decline." Canadian Journal of Zoology 73, no. 4 (April 1, 1995): 713–22. http://dx.doi.org/10.1139/z95-083.
Full textAbstract:
We examined the extent and impact of predation on red squirrels (Tamiasciurus hudsonicus) during a cyclic decline of snowshoe hares in the southwestern Yukon, Canada. We monitored survival of squirrels on three control grids and a predator exclosure from March 1991 through August 1993. On controls, adult survival during the breeding season decreased from 1991, when snowshoe hare populations were high, to 1992, when hare populations declined rapidly. Survival increased slightly in 1993, when hare and predator populations were very low. Similarly, adult survival during winter was lower in 1992 – 1993 than in 1991 – 1992. Adult survival on the exclosure remained similar in each breeding season but declined during winter 1992 – 1993. Adult survival was similar on the controls and the exclosure in each year except during winter 1991–1992 and the 1992 breeding season, when it was lower on the controls. There was no difference in juvenile survival between the controls and the exclosure. Despite the decrease in adult survival due to predation, there was no population decline on any of the control grids. We conclude that predation did not have a measurable impact on red squirrel densities at Kluane and that it is unlikely red squirrels show 10-year population cycles in conjunction with snowshoe hares.
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MOORE, Oliver, and Michael J. CRAWLEY. "Red deer exclusion and saxicolous cryptogam community structure." Lichenologist 46, no. 2 (February 11, 2014): 229–44. http://dx.doi.org/10.1017/s0024282913000868.
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AbstractDeer exclosure is an important management strategy for encouraging woodland regeneration in the presence of high numbers ofCervus elaphusL. This could pose a threat to important saxicolous lichen communities as a result of competition from bryophytes and other vegetation. This investigation compared the bryophyte and lichen communities associated with siliceous rock outcrops and boulders inside and outside a number of exclosures in wet heath vegetation at the Gruinard, Letterewe and Little Gruinard estates in Wester Ross. Species cover data were recorded from 6600·2×0·2 m quadrats, allocated to three different aspects of rocks, from 22 pairs of plots (placed either side of a deer fence) with randomization at each level of this hierarchy. The data were analyzed using linear mixed effects models. Mean lichen cover, diversity and species richness were significantly lower in quadrats on rocks within the exclosures. Mean bryophyte cover was significantly higher in quadrats on rocks inside the deer fence and was shown to have a highly significant negative relationship with total lichen cover. Saxicolous lichen species are particularly affected by the increase in shading and litter accumulation from the surrounding plants and the subsequent growth of bryophytes and heath vegetation on rocks within the exclosures. The results of this study have implications for the use of exclosures at locations where there are important saxicolous lichen communities.
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Tsegay, Gedion, and Xiang-Zhou Meng. "Impact of Ex-Closure in above and below Ground Carbon Stock Biomass." Forests 12, no. 2 (January 24, 2021): 130. http://dx.doi.org/10.3390/f12020130.
Full textAbstract:
Globally, there is a serious issue in carbon stock due to high deforestation and the loss of land, limited carbon storage pools in aboveground and underground forests in different regions, and increased carbon emissions to the atmosphere. This review paper highlights the impact of exclosures on above and below ground carbon stocks in biomass as a solution to globally curb carbon emissions. The data has been analyzed dependent on the Intergovernmental Panel on Climate Change (IPCC) guidelines, the Food and Agriculture Organization (FAO) Forest Resource Assessment report (FRA, 2020), and scientific journal publications mostly from the last decade, to show the research results of carbon stock and the impact of exclosures, particularly the challenges of deforestation and erosion of land and opportunities of area exclosures to provide a general outlook for policymakers. Overall, the world’s forest regions are declining, and although the forest loss rate has slowed, it has still not stopped sufficiently because the knowledge and practice of exclosures are limited. The global forest loss and carbon stock have decreased from 7.8 million ha/yr to 4.7 million ha/yr and from 668 gigatons to 662 gigatons respectively due to multiple factors that differ across the regions. However, a move toward natural rehabilitation and exclosures to reduce the emissions of Greenhouse Gas (GHGs) is needed. In the global production of carbon, the exclosure of forests plays an important role, in particular for permanent sinks of carbon.
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Freudenberger, D., and RB Hacker. "The Effect of Temporary Closure of Watering Points on Grazing Intensity of Red and Grey Kangaroos With Related Observations on Feral Goats." Rangeland Journal 19, no. 2 (1997): 157. http://dx.doi.org/10.1071/rj9970157.
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In this study we examined the utility of manipulating artificial waters as a means of managing total grazing pressure in semi-arid rangelands of eastern Australia. We tested the efficacy of 'Finlayson trough' exclosure technology at three locations, over two summers, in paddocks with red kangaroos (Macropus rufirs) and two species of grey kangaroo (M. giganteus and M. fuliginosus). We also examined the effect of closing off five waters on the distribution of feral goat grazing intensity at one study site. Generally, there were no apparent reductions in kangaroo and goat grazing intensity following 6-10 weeks of water exclosure, the exception being a minor reduction in red kangaroo grazing intensity at one location. We concluded that kangaroo and goat grazing pressure cannot be substantially reduced by simply closing off waters in and near paddocks for several months. Key words: kangaroos, water exclosure. feral goats, grazing pressure, paddock spelling
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Ringmark, Skarin, and Jansson. "Impact of Year-Round Grazing by Horses on Pasture Nutrient Dynamics and the Correlation with Pasture Nutrient Content and Fecal Nutrient Composition." Animals 9, no. 8 (July 29, 2019): 500. http://dx.doi.org/10.3390/ani9080500.
Full textAbstract:
Horse grazing may benefit biodiversity, but the impact of year-round grazing on nutrient dynamics has not been evaluated previously. This study compared pasture quality in a forest-grassland landscape grazed year-round by horses with that in exclosed mown areas. Twelve Gotlandsruss stallions were kept without supplementary feeding in three enclosures (~0.35 horse/ha) outside Uppsala, Sweden, from May 2014 to September 2016. Each enclosure contained three mown exclosures, where grass sward samples were collected monthly and analyzed for chemical composition and vegetation density. Fecal grab samples were collected and analyzed for crude protein (CP) and organic matter (OM) content. There were no differences in exclosure pasture energy or CP content between enclosures (p > 0.05). In grazed areas, there were differences in grass energy and CP content (p > 0.05) between enclosures. During the three summers studied, energy and CP content increased in the enclosures, but decreased in the exclosures. By the end, biomass content/ha was greater in the enclosures than in the exclosures. Fecal OM and CP content showed moderate to strong correlations with pasture nutrient content (r = 0.3–0.8, p < 0.05). Thus, in contrast to monthly mowing, horse grazing diversified pasture chemical composition and increased its nutritive value.
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Holmes, Stacie A., Christopher R. Webster, David J. Flaspohler, and Robert E. Froese. "Death and Taxus: the high cost of palatability for a declining evergreen shrub, Taxus canadensis." Canadian Journal of Forest Research 39, no. 7 (July 2009): 1366–74. http://dx.doi.org/10.1139/x09-064.
Full textAbstract:
Taxus canadensis Marsh., a shade-tolerant evergreen shrub, is in decline as a result of past anthropogenic disturbances and increased cervid browsing. To identify factors that may be influencing establishment for this species, we planted 1080 T. canadensis cuttings in a hemlock–hardwood forest in the spring of 2004. Cuttings were planted across a gradient of light environments, consisting of artificial canopy gaps (61–441 m2) and closed-canopy conditions, and half were protected with deer exclosures. Following four growing seasons, T. canadensis survival in exclosures was 92% compared with 75% in controls. A mixed-effects binary logistic regression analysis revealed that deer exclusion had the most influence on the probability of survival; all else being equal an individual was nearly seven times more likely to survive if planted inside an exclosure (P < 0.001). Increasing light intensity had a counterbalancing effect on growth and survival; light increased leader growth (P = 0.019) but reduced an individual’s probability of survival (P < 0.001), possibly owing to enhanced herbivory and elevated moisture stress. Consequently, enhancing resource availability and growth may not decrease the impact of biomass loss to herbivory. These results suggest that even with relatively low herbivore densities, exclosures are required for the recovery of highly palatable species.
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Orr, DM, and CJ Evenson. "Effects of Sheep Grazing Astrebla Grasslands in Central Western Queensland. Iii. Dynamics of Astrebla Spp. Under Grazing and Exclosure Between 1975 and 1986." Rangeland Journal 13, no. 1 (1991): 36. http://dx.doi.org/10.1071/rj9910036.
Full textAbstract:
The basal area, yield and plant populations of Astrebla spp. were monitored under grazing and exclosure in Astrebla grasslands between 1975 and 1986. This study was undertaken to develop an understanding of how Astrebla spp. respond to grazing, particularly in relation to the high variability of rainfall. Basal area and yield of Astrebla spp. varied widely between years in response to summer rainfall, with few differences between exclosure and grazing. The failure of summer rainfall resulted in increased utilization of Astrebla spp. but this effect was partially offset in some years by the growth of forb species following winter rainfall. Grazing stimulated the recruitment of Astrebla spp. seedlings by increasing the density of inflorescences which, in turn, increased seed production. Survival of seedling cohorts depended on adequate summer rainfall and grazing tended to enhance cohort survival. There was a greater plant flux under grazing than under exclosure. It was concluded that rainfall is the major factor influencing the biomass and plant population dynamics of Astrebla spp. and that grazing up to about 30% utilization is not detrimental to Astrebla spp.
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Halofsky, Joshua, and William Ripple. "Trophic Cascades and Historic Aspen Recruitment in the Gallatin Elk Winter Range of Southwest Montana." UW National Parks Service Research Station Annual Reports 29 (January 1, 2005): 89–95. http://dx.doi.org/10.13001/uwnpsrc.2005.3621.
Full textAbstract:
The extirpation of the gray wolf (Canis lupus) by 1930 in Yellowstone National Park (YNP) provided us with an opportunity to study historic aspen (Populus tremuloides ) recruitment with and without a top carnivore predator present. Herbivory, climate trends, fire records, and current conifer invasion were also examined within the context of aspen recruitment. We obtained tree cores and diameter at breast height measurements to create an aspen age-diameter relationship which we used to approximate aspen origination dates. One elk (Cervus elaphus) exclosure, erected in 1945 within the same elk winter range, was compared to the rest of the winter range. Consistent recruitment inside the exclosure began in the 1940s and has continued into the present. Outside of the exclosure, aspen recruitment began decreasing in the 1930s and ceased in the 1950s. Within the scope of the study, we found little correlative evidence between aspen decline and climate trends, conifer invasion, or fire suppression. The results are suggestive of a trophic cascade between aspen recruitment, and historical elk browsing activities as affected by the absence or presence of wolf predation.
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Evans, Piers, Emma L. Davis, Ze'ev Gedalof, and Carissa D. Brown. "Small herbivore exclosure cages alter microclimate conditions." Forest Ecology and Management 415-416 (May 2018): 118–28. http://dx.doi.org/10.1016/j.foreco.2018.02.012.
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Cisneros, J. M., J. J. Cantero, and A. Cantero. "Vegetation, soil hydrophysical properties, and grazing relationships in saline-sodic soils of Central Argentina." Canadian Journal of Soil Science 79, no. 3 (August 1, 1999): 399–409. http://dx.doi.org/10.4141/s98-055.
Full textAbstract:
Land use and grazing regime can influence the dynamic of soil water and salt in humid areas. In Central Argentina, more than 2 ×106 ha are subjected to either permanent or cyclical processes of land salinization, alkalinization, flooding and sedimentation. In this region, the natural vegetation is the principal resource on which most systems of animal production are based. The objective of this study was to evaluate the effects of plant cover and grazing over some hydrophysical properties of three saline-sodic soils (two Gleic Solonetz in duripan phase and one Mollic Solonetz in fragipan phase), within a catena sequence. The effects on bulk density, saturated hydraulic conductivity, infiltration runoff, superficial salt accumulation and soil salinity distribution were determined in both bare and covered soil conditions, inside and outside of grazing exclosures. The results showed increased bulk density of topsoil for bare conditions, while saturated hydraulic conductivity did not show significant differences. In soils without any cover, the infiltration decreased significantly. Consequently, the runoff coefficient and salinity were greater, as indicated by significant salt accumulation in the topsoil. The soil profile salinity was reduced as a function of exclosure time, showing a trend toward desalinization resulting from a combined effect of soil cover and changes in intensity of land use. A conceptual model of salt and water dynamics in the soil profile for the landscape scale is postulated. The role of vegetation in regulating water and salt movement in poorly drained areas is emphasised as a basis for the development of management strategies. Key words: Saline and sodic soils, infiltration, runoff, grazing, exclosure, model
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Prietzel, Jörg. "Schutzwälder der Nördlichen Kalkalpen: Verjüngung, Mikroklima, Schneedecke und Schalenwild | Protection forests in the Northern Limestone Alps: stand regeneration, microclimate, snow cover and ungulates." Schweizerische Zeitschrift fur Forstwesen 161, no. 1 (January 1, 2010): 12–22. http://dx.doi.org/10.3188/szf.2010.0012.
Full textAbstract:
Relationships among ungulate pressure, stand regeneration, microclimate, and snowpack dynamics were investigated at three protection forest sites in the mixed mountain forest zone of the Bavarian Limestone Alps. The study was conducted at plots located inside and outside ungulate exclosures which had been established about 35 years ago. Air and topsoil temperatures were recorded for one year in hourly intervals. In winter 2005/2006, the thickness, constitution, and mobility of the snowpack were investigated. Inside the exclosures, which were stocked with dense regeneration of mixed mountain forest, mean air and topsoil temperatures were up to 0.9 °C (air) and 1.9 °C (soils) lower than outside. Maximum daily values of air and topsoil temperatures were up to 1.4 °C (air) and 5.2 °C (soils) lower inside the exclosures compared to the respective outside plots. The temperature differences were dependent on the aspect (NW < ESE < S). Snowpack thickness during winter increased more slowly inside the exclosures than outside due to snow interception by the young trees which had developed during stand regeneration; in late winter, snowpack melting was retarded. Inside the exclosures the snowpack was more heterogeneous (“column structure”) than outside (laminated structure). Consequently, inside the exclosures a large portion of the melting water drained vertically to the bottom of the snowpack and infiltrated into the soil, and the snow gliding activity was significantly smaller than outside. In summary, particularly at S-exposed sites, exclosure of ungulates resulted in a cooler, less extreme microclimate, a more heterogeneous and stable snowpack, and reduced snow gliding. Therefore, an adequate regulation of ungulate density by appropriate hunting activity is a key factor for a sustainable provision of important protection services of the mixed mountain forest in the Northern Limestone Alps.
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Zou, J., L. Zhao, S. Xu, X. Xu, D. Chen, Q. Li, N. Zhao, C. Luo, and X. Zhao. "Livestock exclosure with consequent vegetation changes alters photo-assimilated carbon cycling in a <i>Kobresia</i> meadow." Biogeosciences Discussions 10, no. 11 (November 12, 2013): 17633–61. http://dx.doi.org/10.5194/bgd-10-17633-2013.
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Abstract. Livestock exclosure has been widely used as an approach for grassland restoration. However, the effects of exclosure on grassland are controversial and can depend on many factors, such as the grassland ecosystem types, evolutionary history and so on. In this study, we conduct field experiments to investigate the variations of ecosystem function in response to livestock exclosure in a Kobresia humilis meadow under six years grazing exclosure on the Qinghai-Tibetan plateau. We focused on two ecosystem functions: plant community structure and ecosystem carbon cycling. The plant aboveground productivity, plant diversity and the composition of plant functional groups of the meadow were addressed as the indicators of the plant community structure. The 13C isotope pulse labeling technique was applied to evaluate the alterations of ecosystem carbon cycling during the short-term. The results showed that the plant community structure was changed after being fenced for six years, with significantly decreased aboveground productivity, species loss and varied composition of the four plant functional groups (grasses, sedges, legumes and forbs). Using the pulse labeling technique, we found a lower cycling rate of 13C in the plant–soil system of the fenced plots compared with the grazed sites during the first 4 days after labeling. A higher proportion of 13C amount recovered in the plant–soil system were migrated into soil as root exudates immediately after labeling at both fenced and control grazed sites, with significantly lower proportion in the fenced site, coinciding with the lower loss of 13C in soil respiration. Thirty-two days after labeling, 37% of recovered 13C remained in the soil of the fenced plots, with significant differences compared to the grazed plots (47%). In addition, less 13C (5% vs. 7%) was lost by soil respiration in the fenced plots during the chase period of 32 d. Overall, our study suggested that livestock exclosure had negative effects on the two ecosystem functions investigated, and the effects on 13C cycling and sequestrations in the soil were in response to variations in community structures, especially the suppression of forbs and legumes in the fenced site.
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Yamada, Hodaka, and Seiki Takatsuki. "Effects of Deer Grazing on Vegetation and Ground-Dwelling Insects in a Larch Forest in Okutama, Western Tokyo." International Journal of Forestry Research 2015 (2015): 1–9. http://dx.doi.org/10.1155/2015/687506.
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Sika deer (Cervus nippon) have experienced a rapid increase in the Japanese archipelago. Although the effects of deer grazing have been widely studied, the indirect effects have received little attention. Using an eight-year-old deer exclosure in western Tokyo (Japan), we studied the direct effects on plants and the indirect effects on insects and microenvironments. Plant biomass was 14 times higher inside the exclosure than outside. Shrubs (e.g.,Aralia elataandHydrangea paniculata) and trees (e.g.,Symplocos sawafutagiandClethra barbinervis) were more abundant inside, whereas only unpalatable trees in poor condition grew outside (e.g.,Pterostyrax hispidaandCynanchum caudatum). In the summer months, the maximum temperature was 8–10°C higher outside the exclosure and humidity was lower. Soil movement was 80 times more pronounced outside than inside. These results suggest that the abiotic environment became less stable for ground-dwelling insects. Carabid beetles were less abundant outside than inside, suggesting that deer grazing reduced plants and subsequently lowered habitat quality for these beetles. In contrast, carrion beetles, dung beetles, and camel crickets were more abundant outside. The increase in these insects is attributed to the availability of deer feces and carcasses and is a direct effect of deer presence.
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Halofsky, Joshua, and William Ripple. "Aspen Recruitment and Stand Structure in the Gallatin Elk Winter Range of Southwest Montana." UW National Parks Service Research Station Annual Reports 28 (January 1, 2004): 98–102. http://dx.doi.org/10.13001/uwnpsrc.2004.3585.
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This study examines the relationship between wolf, elk, and aspen within the framework of trophic cascades inside and outside of the Gallatin elk winter range. The overall goal of this study is to determine if an association exists between aspen recruitment, and historic and current elk browsing activities as affected by the absence or presence of wolf predation. This study also examines if other factors (climate fluctuations, conifer invasion, ftre suppression) may have had a role in aspen decline. Through the examination of current and historic elk browsing levels, current and historic browsing effects on aspen recruitment are addressed. Potential historic browsing affects were assessed with tree rings, aspen age structures, historic documents, and an elk exclosure erected in 1945. Current browsing levels were assessed through plant architecture methods and elk pellet counts. Initial results indicate that a gap in aspen recruitment is present yet aspen have successfully recruited inside an elk exclosure located within the same elk winter range. The lack of recruitment outside the exclosure appears to be due to chronic elk herbivory, although other factors need further evaluation. Future results will elucidate if the recruitment gap occurred after wolf extirpation in the 1920's.
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Pinto, SRR, AMM Santos, and M. Tabarelli. "Seed predation by rodents and safe sites for large-seeded trees in a fragment of the Brazilian Atlantic forest." Brazilian Journal of Biology 69, no. 3 (August 2009): 763–71. http://dx.doi.org/10.1590/s1519-69842009000400003.
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Seed predation by small rodents is an emerging theme in the ecology of modified landscapes. Here we investigate the role played by the small rodent Oryzomys oniscus as a seed predator of large-seeded trees in a large remnant of the Atlantic forest - the Coimbra forest (3,500 ha), Alagoas state, northeastern Brazil. O. oniscus was captured and identified by setting twenty 500 m long transects, each one composed of 25 traps 20 m apart. This procedure resulted in 483 trap-nights set during a 20-mo period. We used 692 seeds (>15 mm length) from ten local large-seeded tree species for the seed predation trials that basically consisted of three treatments: one seed on the ground freely accessed by vertebrates (unprotected seed), one seed totally protected by an exclosure, and one partially-protected seed (exclosure just for medium-sized and large vertebrates). O. oniscus was captured throughout the Coimbra forest including forest edges (76 captures) and interior areas (67), and this small rodent was responsible for all seed predation visually documented inside exclosures. A 24 hours period of seed exposition permitted elevated rates of seed removal and predation. Seeds were much more removed/predated beneath fruiting trees, but rates varied according to the level of seed protection - 26.3% of predation among partially-protected versus 19.2% among unprotected seeds. Seeds suffered higher levels of seed predation/removal at the forest edge as well (up to 90%). In both habitats, most seeds (>84%) remained intact beneath trees without fruits, regardless of the level of seed protection. Our results suggest that O. oniscus may operate as an effective large-seed predator in forest fragments, in which adult trees without fruits constitute low resource spots and thereby provide, at least temporarily, safe sites for large seeds.
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Mercier, Francine, and Raymond McNeil. "Seasonal variations in intertidal density of invertebrate prey in a tropical lagoon and effects of shorebird predation." Canadian Journal of Zoology 72, no. 10 (October 1, 1994): 1755–63. http://dx.doi.org/10.1139/z94-237.
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We analyzed the relationship between the abundance of shorebirds and that of their intertidal invertebrate prey, and attempted to determine if shorebird predation significantly affects prey density. The study was conducted at three sites in the Chacopata Lagoon complex in northeastern Venezuela between January 1985 and September 1986, using shorebird census data, monthly sampling of intertidal invertebrates, and exclosure experiments. The invertebrates collected were divided into three groups: (i) polychaetes (≤50 mm in length), (ii) small bivalves (2 – 3 mm in length), and (iii) other species. The overall density of shorebirds foraging in the Chacopata Lagoon complex was very high, exceeding the densities reported for most other staging and overwintering areas by a wide margin. The abundance of shorebirds in the study area was related primarily to the density of polychaetes, their main prey. At two of the study sites, the arrival of fall migrants followed a significant increase in polychaete numbers. The increase in shorebird numbers in autumn was negligible at the third site, where polychaete density was lower than at the other sites. The impact of shorebird predation on their invertebrate prey varied seasonally, as did the extent of the foraging area available to them. The exclosure experiment revealed significant differences in the density of polychaetes inside and outside the exclosures only during, or shortly after, the fall migration period. The variability in the conclusions drawn from other studies examining prey depletion by shorebirds in tropical environments may be explained by differences in the length of sampling periods and seasonal variations in the numbers of foraging shorebirds, the energy demands of moult, fat deposition, and the intertidal surface area available for feeding. The impact of seasonal variables such as these should be taken into consideration when designing studies to measure prey depletion by shorebirds; such objectives may necessitate long-term studies.
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Greenberg, C. H., and S. J. Zarnoch. "A test of the predator satiation hypothesis, acorn predator size, and acorn preference." Canadian Journal of Forest Research 48, no. 2 (February 2018): 237–45. http://dx.doi.org/10.1139/cjfr-2017-0381.
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Mast seeding is hypothesized to satiate seed predators with heavy production and reduce populations with crop failure, thereby increasing seed survival. Preference for red or white oak acorns could influence recruitment among oak species. We tested the predator satiation hypothesis, acorn preference, and predator size by concurrently measuring acorn production, mouse abundance, and white versus red oak acorn removal rates in exclosures allowing access by mice (HW), squirrels and smaller-sized vertebrates (WW), or all-sized vertebrates (C) for 12 years. Annual removal rate varied, but virtually all acorns were eventually removed from all exclosure types all years except one. Acorns were removed more slowly from HW than from WW or C exclosures, indicating that large vertebrates were not major acorn consumers, locally. Red and white oak acorn removal rates were similar except in two years, when red oak acorns were removed more rapidly. Removal slowed with increasing acorn crops, suggesting that heavy crops can “swamp” predators. Removal rate was negatively correlated with crop size the previous fall. A positive trend between mouse abundance and crop size the previous fall was evident; abundance decreased sharply the year following crop failures but not after moderate or heavy crops, suggesting that poor crops can dampen acorn predation the following year.
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Risenhoover, Kenneth L., and Steven A. Maass. "The influence of moose on the composition and structure of Isle Royale forests." Canadian Journal of Forest Research 17, no. 5 (May 1, 1987): 357–64. http://dx.doi.org/10.1139/x87-062.
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The long-term influence of moose (Alcesalces) on the structure and species composition of three forest types in Isle Royale National Park, Michigan was evaluated using four moose-proof exclosures established in 1949–1950. Results obtained during the present study were compared with the original vegetation at each study site and with data collected by Krefting (1974) in order to discriminate between the effects of moose browsing and forest community succession. In the spruce–birch–fir climax and aspen–birch–conifer forest study sites, self-thinning and reduced light availability reduced the density of woody plant stems in exclosure areas. In the adjacent control areas, moose browsing has slowed the rate of succession. Repeated browsing by moose on palatable species has retarded vertical growth and has prevented stems from growing beyond reach. Effects of moose browsing on succession in the aspen–birch study sites in the 1936 burn were less clear. In all three forest types, stem densities of most species were higher in control areas than in exclosures. Species diversity was also greater in control areas. American yew (Taxuscanadensis) and red-osier dogwood (Cornusstolonifera) were the only species that declined in abundance as a result of browsing by moose.
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Byrom, Andrea E., Tim J. Karels, Charles J. Krebs, and Rudy Boonstra. "Experimental manipulation of predation and food supply of arctic ground squirrels in the boreal forest." Canadian Journal of Zoology 78, no. 8 (August 1, 2000): 1309–19. http://dx.doi.org/10.1139/z00-055.
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We examined whether arctic ground squirrel (Spermophilus parryii plesius) populations in northern boreal forest in the Yukon Territory, Canada, were limited by food, predators, or a combination of both, during the decline and low phases of a snowshoe hare cycle. From 1990 to 1995, populations were monitored in large-scale (1 km2) experimental manipulations. Squirrels were studied on eight 9-ha grids: four unmanipulated control grids, two food-supplemented grids, a predator-exclosure grid, and a predator-exclosure + food-supplemented grid. Population density was measured on all grids by livetrapping and active-season survival was measured using radiotelemetry. Population densities were lowest in 1992 and 1993 (2 years after the snowshoe hare population decline). Rates of population change were negative from 1991 to 1993, when predation pressure was most intense after the snowshoe hare decline, and positive from 1993 to 1995, when hares and predators were at low densities. Predation accounted for 125 of 130 mortalities (96%) of radio-collared squirrels. Adult survival was significantly lower in 1992 and 1993 than in 1994 and 1995, and was a strong predictor of annual rates of population change in arctic ground squirrels. Treatments were ranked as follows in their effect on adult survival: predator exclosure + food-supplemented > food-supplemented > predator exclosure > controls. Juvenile survival was lowest in 1992, and food addition and predator removal separately increased juvenile survival. On average, predator exclusion increased population densities twofold, food supplementation increased densities fourfold, and food supplementation and predator removal together increased densities 10-fold. We conclude that food and predation interact to limit arctic ground squirrel populations in the boreal forest during the decline and low phases of the snowshoe hare cycle. The snowshoe hare cycle may indirectly create a lagged secondary fluctuation in arctic ground squirrel populations through shared cyclic predators.
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Camargo-Sanabria, Angela A., Eduardo Mendoza, Roger Guevara, Miguel Martínez-Ramos, and Rodolfo Dirzo. "Experimental defaunation of terrestrial mammalian herbivores alters tropical rainforest understorey diversity." Proceedings of the Royal Society B: Biological Sciences 282, no. 1800 (February 7, 2015): 20142580. http://dx.doi.org/10.1098/rspb.2014.2580.
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It has been suggested that tropical defaunation may unleash community-wide cascading effects, leading to reductions in plant diversity. However, experimental evidence establishing cause–effect relationships thereof is poor. Through a 5 year exclosure experiment, we tested the hypothesis that mammalian defaunation affects tree seedling/sapling community dynamics leading to reductions in understorey plant diversity. We established plot triplets ( n = 25) representing three defaunation contexts: terrestrial-mammal exclosure (TE), medium/large mammal exclosure (PE) and open access controls (C). Seedlings/saplings 30–100 cm tall were marked and identified within each of these plots and re-censused three times to record survival and recruitment. In the periods 2010–2011 and 2011–2013, survival was greater in PE than in C plots and recruitment was higher in TE plots than in C plots. Overall, seedling density increased by 61% in TE plots and 23% in PE plots, whereas it decreased by 5% in C plots. Common species highly consumed by mammals (e.g. Brosimum alicastrum and Ampelocera hottlei ) increased in their abundance in TE plots. Rarefaction curves showed that species diversity decreased in TE plots from 2008 to 2013, whereas it remained similar for C plots. Given the prevalence of tropical defaunation, we posit this is an anthropogenic effect threatening the maintenance of tropical forest diversity.
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Atwill, Edward R., Neil K. McDougald, Ralph L. Phillips, and Doug McCreary. "Exclosure size affects young blue oak seedling growth." California Agriculture 61, no. 1 (January 2007): 16–19. http://dx.doi.org/10.3733/ca.v061n01p16.
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Rossiter, John, Markos Wondie Minale, Workneh Andarge, and Stephen Twomlow. "A communities Eden – grazing Exclosure success in Ethiopia." International Journal of Agricultural Sustainability 15, no. 5 (July 16, 2017): 514–26. http://dx.doi.org/10.1080/14735903.2017.1352059.
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Gallego, Federico, José M. Paruelo, Santiago Baeza, and Alice Altesor. "Distinct ecosystem types respond differentially to grazing exclosure." Austral Ecology 45, no. 5 (February 28, 2020): 548–56. http://dx.doi.org/10.1111/aec.12870.
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Gawne, B. "Effects of feeding by Agapetus species (Trichoptera) on the density of epilithon in an Australian upland stream." Marine and Freshwater Research 46, no. 7 (1995): 991. http://dx.doi.org/10.1071/mf9950991.
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The effects of feeding by an abundant glossosomatid trichopteran on the density of epilithon on cobbles in an upland stream were evaluated by using both exclosures and flow-through in-stream channels. The in-stream channel experiment found that Agapetus kimminsi Banks had the ability to reduce significantly the density of epilithon on experimental substrata and that this effect was more pronounced on the sides of experimental substrata. The exclosure experiment found that excluding Agapetus monticolus Banks from experimental substrata within the stream had no effect on epilithon density. The different results from the two experiments appear to be due to the use of different experimental protocols and indicate that although Agapetus species are capable of affecting the density of epilithon, they may have only a limited effect within the stream. The limited effect of Agapetus species on the density of epilithon may be due to the effects of other environmental factors (e.g. current) both on the foraging activities of Agapetus species and on the density of epilithon.
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Page, Kimberley D., Laura Ruykys, David W. Miller, Peter J. Adams, Philip W. Bateman, and Patricia A. Fleming. "Influences of behaviour and physiology on body mass gain in the woylie (Bettongia penicillata ogilbyi) post-translocation." Wildlife Research 46, no. 5 (2019): 429. http://dx.doi.org/10.1071/wr18105.
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Context Temperament can affect an individual’s fitness and survival if it also influences behaviours associated with predator avoidance, interactions with conspecifics, refuge selection and/or foraging. Furthermore, temperament can determine an individual’s response to novel stimuli and environmental challenges, such as those experienced through translocation. Increasing our understanding of the effect of temperament on post-translocation fitness is thus necessary for improving translocation outcomes. Aims The aim was to test whether differences in an individual’s behaviour or physiology could help predict body mass changes post-translocation in the woylie (brush-tailed bettong, Bettongia penicillata ogilbyi). In the absence of predation (due to release into a predator-free exclosure), body mass was used as a proxy for an individual’s success in securing resources in the new habitat, and therefore fitness. Methods Forty woylies were translocated from two predator-free exclosures to a larger exclosure, all in Western Australia. Behavioural and physiological measures were recorded during trapping, processing, holding, and release, and again at re-capture ~100 days post-release. Key results Translocated woylies generally increased in body mass post-translocation. This suggests that, in the absence of predation, the selected candidates were able to cope with the stress of translocation and possessed the behavioural plasticity to successfully find resources and adapt to a novel environment. The strongest predictors of body mass gain were sex, heart rate lability and escape behaviour when released (a convoluted escape path). Conclusions There was no significant difference in body mass between males and females pre-translocation but females showed greater mass gain post-translocation than did males, which could reflect greater investment in reproduction (all females had pouch young). Heart rate lability and escape behaviour are likely to reflect reactivity or fearfulness, a significant temperament trait in the context of translocation success. Implications Behavioural measures that can be easily incorporated into the translocation process – without increasing stress or affecting welfare of individuals – may hold promise for predicting the fate of translocated animals.
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Murphy, Robert K., Isabelle M. G. Michaud, David R. C. Prescott, Jacob S. Ivan, Beverly J. Anderson, and Marlanea L. French-Pombier. "Predation on Adult Piping Plovers at Predator Exclosure Cages." Waterbirds 26, no. 2 (2003): 150. http://dx.doi.org/10.1675/1524-4695(2003)026[0150:poappa]2.0.co;2.
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Slack, William T., and Martin T. O'Connell. "Design for a Portable, Modular Stream Enclosure/Exclosure Device." Journal of Freshwater Ecology 13, no. 2 (June 1998): 193–206. http://dx.doi.org/10.1080/02705060.1998.9663607.
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